What is the normal leakage current when measured with a multimeter?
2 Answers
The normal leakage current for vehicles is generally around 40mA. However, this can vary depending on the vehicle model, and some high-end cars may have a leakage current of up to 80mA. There is a normal range for vehicle leakage current, and exceeding this range can not only affect the normal operation of onboard electrical appliances but also make it difficult to start the engine. Before using a multimeter, it is essential to perform a "mechanical zero adjustment," which means setting the multimeter pointer to the zero voltage or zero current position when there is no measured electrical quantity. Additionally, the multimeter must be placed horizontally during use to avoid errors. It is also important to avoid the influence of external magnetic fields on the multimeter. Measurement method: Turn off and disconnect all electrical appliances, use the multimeter's RX10K range, connect one probe to the live wire being tested and the other probe to the ground (or a water faucet). The display should show infinite resistance; otherwise, there is leakage. Advantages of automotive multimeters: The main advantages are portability, ease of use, and the ability to measure multiple parameters effectively, making them popular among automotive repair technicians for measuring vehicle data. Automotive repairs often require measuring not just resistance, voltage, and voltage drops but also checking engine frequency, pressure, semiconductor components, current, duty cycle, and other data to assess circuit continuity and the condition of electrical equipment, enabling timely detection of vehicle faults.
I often tinker with my car's electrical system myself, like using a multimeter to measure leakage current. It's quite simple: set the multimeter to the current range (milliampere mA), disconnect the negative battery terminal, and connect the measuring leads in series. Generally, a normal reading below 50 mA is considered safe. I've seen many cars fluctuate between 20-50 mA, which is quite common. If it exceeds 50 mA, you should be cautious—it might be due to aging wiring, a short circuit, or forgetting to turn off a device, which can drain the battery or even cause sparks. I'd recommend testing it regularly, checking every few months to catch issues early and avoid being stranded on the road. Remember, when measuring, make sure all switches in the car are locked—safety first to prevent unexpected trouble.
